1. Field of the Invention
Embodiments of the present invention relate to a semiconductor device that includes a semiconductor module including, for example, a power device and has a common external connection structure and a method for manufacturing a semiconductor device.
2. Discussion of the Background
A power inverter device has been widely used as one of power conversion devices. For example, a motor is generally used as a driving source of an electric vehicle and the inverter device is generally used to control this type of motor.
A semiconductor module including a power device, such as an insulated gate bipolar transistor (IGBT) or a free wheeling diode (FWD), is used in the power conversion device.
FIG. 19 is a cross-sectional view illustrating an example of a semiconductor module according to the related art. In the semiconductor module according to the related art illustrated in FIG. 19, a semiconductor chip 11, such as an IGBT or an FWD, is bonded to an insulating substrate 12. The insulating substrate 12 is, for example, a ceramic substrate and conductor layers 12a and 12b are formed on the front and rear surfaces of the insulating substrate 12, respectively. The semiconductor chip is bonded to the conductor layer 12a on the front surface which is a first main surface. In addition, the conductor layer 12b on the rear surface, which is a second main surface of the insulating substrate 12, is bonded to a base plate 13 made of a material with high thermal conductivity. A surface of the base plate 13 that is opposite to the surface to which the insulating substrate 12 is bonded is fixed to the radiation fin 14, with a compound or a sheet with high thermal conductivity interposed therebetween.
On the front surface side of the insulating substrate 12, the conductor layer 12a forms a circuit pattern, is bonded to an electrode on the rear surface of the semiconductor chip 11, and is generally bonded to an electrode on the front surface of the semiconductor chip 11 by an aluminum wire 15. In addition, a plurality of external terminals 16a to 16c are connected to the conductor layer 12a on the insulating substrate 12.
A frame-shaped resin case 17 is fixed to the base plate 13 by, for example, an adhesive so as to surround the insulating substrate 12. A sealing material 18, such as silicon gel, fills the resin case 17 and the base plate 13 so as to cover, for example, the semiconductor chip 11. Then, a cover 17a is fixed so as to close an opening of the resin case 17 and the semiconductor chip 11 or the internal wiring structure is protected by an external environment.
In recent years, with the spreading of renewable power generation facilities for reducing power consumption, there is an increasing demand for a power conversion semiconductor device. In particular, it is a challenge to increase capacity or a breakdown voltage in the above-mentioned semiconductor module.
That is, in the above-mentioned semiconductor device, a plurality of semiconductor chips 11 are arranged on the conductor layer 12a on the insulating substrate 12 and the semiconductor chips 11 are connected to each other by the aluminum wire 15 to achieve a parallel or series connection structure. As a result, high capacity or a high breakdown voltage is obtained. In addition, a plurality of insulating substrates 12 are mounted on the base plate 13 and the conductor layers 12a on the insulating substrates 12 and the semiconductor chips 11 are connected to each other by the aluminum wires 15. In this way, a parallel or series circuit structure is achieved and high capacity or a high breakdown voltage is obtained. The semiconductor module is a large semiconductor module which is formed as a circuit structure with desired capacity or breakdown voltage.
In order to transfer heat (loss) generated from the semiconductor chip 11 to the base plate 13 and to dissipate the heat to the outside of the system with high efficiency, the base plate 13 needs to be fixed to the radiation fin 14 by a plurality of bolts 19, and the base plate 13 and the radiation fin 14 need to be held while coming into pressure contact with each other (for example, see JP 2007-194442 A) (“Patent Document 1”).
JP 2004-289103 A (“Patent Document 2”) and JP 2010-251772 A (“Patent Document 3”) disclose a semiconductor device which can ensure high yield using a wide band gap semiconductor in which yield is reduced due to crystal defects in a wafer and can be manufactured at a low cost. Here, in a semiconductor module, segments (semiconductor element) which can individually operate are provided on a silicon carbide (SiC) substrate and an element separation region, such as a trench or a Schottky diode, for electrically separating adjacent segments is provided. In the semiconductor module, only the electrode pad of the segment which has passed a test is connected to the electrode terminal.
JP 2007-209184 A (“Patent Document 4”) discloses a power conversion device, which includes a bus bar that connects a power conversion circuit and an external device, and a base that fixes at least a power module and a control substrate. In the power conversion device, modules corresponding to one arm are fixed to a common base and are connected to each other by the bus bar. Here, the power conversion device has an optimum structure corresponding to an attachment space, which results in an increase in flexibility in the mounting of the power conversion device to, for example, the engine room of the vehicle with many spatial constraints. In addition, the rigidity of the control substrate increases and vibration resistance increases. Furthermore, it is possible to improve a cooling effect.
JP 2006-81308 A (“Patent Document 5”) discloses a technique related to a power drive unit including a plurality of power modules. The power drive unit includes a radiator plate to which the plurality of power modules and a current detection unit are connected in parallel. In addition, the power drive unit includes insertion holes into which positioning pins provided in the power module and positioning pins formed on an electronic circuit board are inserted. Here, it is possible to connect one electronic circuit board and a plurality of power modules once (at the same time) and to easily assemble them. Therefore, the efficiency of an assembly operation is improved.
JP 05-218252 A (“Patent Document 6”) and JP 07-123738 A (“Patent Document 7”) disclose a structure in which the external terminals of modules are connected by a connection conductor such as a bus bar.
For example, it is necessary to form a full-bridge circuit using the semiconductor device illustrated in FIG. 19 as follows. That is, in the semiconductor device illustrated in FIG. 19, the external terminals 16a to 16c exposed from the cover 17a are connected by a wiring substrate which is provided outside the semiconductor device or an external connection conductor, such as a bus bar, and the individual semiconductor devices are wired to form external lead terminals for output and input power sources (for example, see Patent Document 6).
However, in the semiconductor device with a single module, the number of insulating substrates 12 or the internal arrangement of the external terminals 16a to 16c is determined by the internal structure of the semiconductor device depending on the usage of the semiconductor device, and there are restrictions in the outward shape of the external connection conductor or the entire semiconductor device in the external structure of the semiconductor device. Therefore, various types of semiconductor chips 11, insulating substrates 12, external terminals 16a to 16c, resin cases 17, and covers 17a corresponding to current capacities required for each rating level need to be prepared in order to satisfy types for each rating level. As a result, production efficiency is reduced.